Description

SpaceChem is a puzzle game about chemical engineering in reactors. It consists of over fifty puzzles divided over different planets, with an overarching story about a reactor engineer working for SpaceChem, a chemical synthesizer for frontier colonies set in outer space. The story is shown in text for each mission.

All levels take place inside a reactor, shown as a board of 10x8 tiles. Although starting conditions often vary, most reactors have two input and output areas. The goal is to develop an instruction that takes one or more atoms from the input zones, manipulates them, and outputs them correctly as a molecule. For instance: the player uses an Ag and an F atom from two input zones to output the bonded molecule Ag-F. The input atoms are shown on the left, and the intended output on the right.

The player has to design the instruction by drawing a line for the routine. Waldos move over the line and grab, move, rotate or drop atoms. The player has to introduce these actions by placing instructions on the routine. In design, it is similar to games such as The Incredible Machine series where you draw a solution, test it, and then redesign the parts that provide an error, to form a complex routine. There are many conditions that need to be taken into account, such as grabbing and dropping atoms at specific locations to bond them, and syncing the waldos to make sure they do not interfere incorrectly. The instruction also needs to work repeatedly, for a set amount of cycles, and not only just a single time.

In later levels multiple reactors are used simultaneously. From an overall map the player dives into a single reactor to form an instruction, outputs it correctly to a next reactor, and designs a new routine with the newly-formed molecule there. These later levels require further thinking and trial and error. The game encourages players to find the most efficient solutions by keeping track of the elapsed cycles, reactors used and symbols used. Next to the main level progression there are twelve additional challenges (achievements) that involve completing missions with specific requirements, such as using a limited amount of cycles, using only one reactor, or finishing optional assignments.